Battery

ABSTRACT

The metal foil of the positive electrode  1   a  or the negative electrode  1   b  in the power generating element  1  is connected along the connecting plate portion  2   b  which is folded, twisted, and provided in a protruding condition from the main portion  2   a  of the current-collector connector  2 ; hence the shape of the current-collector connector  2  becomes easy to form, and a battery capable of enhancing current collection efficiency, reliability and workability can be provided.

TECHNICAL FIELD

The present invention relates to a battery having characteristics incurrent-collection structure.

BACKGROUND ART

FIG. 8 shows the conventional connection structure of power generatingelements 1, current-collector connectors 2, and external connectionterminals 3 in a non-aqueous electrolyte secondary battery. In thisnon-aqueous electrolyte secondary battery, two power generating elements1 of an elliptic cylindrical shape are connected in parallel.

Each power generating element 1 such as shown in FIG. 3 is configured bywinding a positive electrode 1 a and a negative electrode 1 b with aseparator 1 c therebetween into an elliptic cylindrical shape. In thepositive electrode 1 a, the surface of a strip aluminum foil 1 d to beused as an electrode substrate is supported with a positive activematerial; and in the negative electrode 1 b, the surface of a stripcopper foil 1 e to be used as an electrode substrate is supported with anegative active material. These positive electrode 1 a and negativeelectrode 1 b are provided with non-coated portions, where the activematerial is not applied to one side-edge portions of the negative stripand to the other side-edge portions of the positive strip, therebyallowing the aluminum foil 1 d and the copper foil 1 e to be exposed inthe non-coated portions. And, in the formation of the power generatingelement 1 by winding, these positive electrode 1 a and negativeelectrode 1 b are wound with being shifted in the opposite directionfrom each other along the winding axis, so that only the aluminum foil 1d at the side-edge portions of the positive electrode 1 a protrudes fromone end face of the elliptic cylindrical shape and only the copper foil1 e at the side-edge portions of the negative electrode 1 b protrudesfrom the other end face.

The above-described two power generating elements 1, 1 are alignedhorizontally so that the flat side of each elliptic cylindrical shapeoverlaps each other in an upright stance. And, at both sides of the endfaces of these power generating elements 1, 1, each electrode isconnected to the current-collector connectors 2, 2 of a ribbed platetype, respectively. The aluminum foil of the positive electrode 1 a orthe copper foil of the negative electrode 1 b protruding from the endface of the power generating element 1 is held in each of the concaveportions of a ribbed plate type, ultrasonic welding is performed, andhence, the electrodes are connected and fixed.

However, there arose a problem in that the use of the above-describedstructure made it difficult for the current-collector connector to beconnected to the power generating element. Moreover, in case of abattery having a large capacity, it is necessary to make a platethickness of the current-collector connector 2 thick enough for a largeamount of electric currents to pass, thereby causing another problem ofeasy occurrence of defective welding when ultrasonic welding wasperformed on the thin aluminum foil or copper foil which was held in it.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to solve these problems andprovide a battery having the current-collector connection structure ofeasy working and high reliability.

The battery of the present invention comprises a battery case, powergenerating elements being configured by overlapping positive andnegative electrodes with an isolation material such as a separatortherebetween, and current-collector connectors being electricallyconnected to said each electrode in said power generating elements,respectively, wherein said current-collector connectors consist of aplate-like main portion and a plurality of connecting plate portionswhich are provided at the edge of the main portion so as to be atapproximately 90 degrees to the main portion, and said connecting plateportions are disposed along the electrode faces at the ends of saidpower generating elements and electrically connected to said electrodes.

In this battery, the connection of the current collectors is made bymeans of the connection between the connecting plate portions and theelectrodes; hence, the connection work is implemented easily.

The above-described connecting plate portions are formed in such amanner that one edge portion of a metal plate is cut into predetermineddimensions and, diverging from the main portion, the cut portions arefolded downward and twisted at approximately 90 degrees so as to be ableto be set along the electrode faces of said power generating elements;hence, by using a current-collector connecting plate of a simplestructure which is made, for example, only by punching, folding, andtwisting a metal plate, it becomes possible to perform effective currentcollection at a low price.

Moreover, with a twist angle being made approximately 90 degrees, itbecomes possible to connect the connection faces of the electrodes alongthe plate faces of the connecting plate portions; hence, the connectioncan be made secured.

In addition, it is desirable that the above-described connecting plateportions be provided in one or more pairs, and that by diverging fromthe metal potion which composes the main portion and by being twisted inthe opposite direction from each other, the sides of each pair of twoconnecting plate portions be made to face each other. With theconnecting plate portions being provided in pairs, the electrode whichprotrudes from the end face of the power generating element is insertedbetween the two connecting plate portions and the connection work iscarried out, thereby allowing the connection work to be easy. Inaddition, twisting the connecting plate portions in the oppositedirection from each other makes it easy to insert the electrode betweenthem, so that the work of fixing the current-collector connecting plateto the power generating element becomes easier.

When connecting plate portions are twisted, it is desirable that thelength of the twisted portions in the protruding direction of theconnecting plate portions be longer than the thickness of the plate ofthe connecting plate portions. When precipitous twisting is applied fora short period of time, stress is concentrated on the twisted portionsof the connecting plate portions, electronic conductivity deteriorates,and the internal resistance of the battery could become high; however,the above consideration can prevent this from occurring.

In addition, it is preferable that protruding convex portions be formedon the surface of the connecting plate portion of the above-describedcurrent-collector connector so as to face the above-described electrodein the above-described power generating element. The formation of theconvex portions allows the welding or crimping of the electrodesubstrates to be centralized on these convex portions, so that itbecomes possible to connect and fix them more firmly.

In addition, it is more preferable to be equipped with pinching plateswhich hold the connecting plate portion of the above-describedcurrent-collector connector and the electrode which is connected to thisportion. The connection portion of the current-collector connector isoverlapped with the electrode substrates of the electrode in the powergenerating element, such overlapped part is held in a pinching plate,and welding or the like can be performed; therefore, it is possible toincrease the section area of this connection portion so that largeamounts of current can pass, and for use as a pinching plate it ispossible to use a metal plate having an adequate thickness for weldingor crimping. Hence, by the use of a thin pinching plate most suitablefor ultrasonic welding and the like, the electrode substrates can befirmly welded to the connection portion of the current-collectorconnector, and connected and fixed; so that there is no fear of thebreak of these electrode substrates. In addition, on the contrary, ifthe thickness of a pinching plate is made sufficiently thick, byapplying firm pressure on this pinching plate from the outside, itbecomes also possible to firmly crimp the electrode substrates and theconnection portion of the current-collector connector, and then connectand fix them. Moreover, the electrode substrates can be held with everyconnection portion of the current-collector connector by means of apinching plate; therefore, the assembly work becomes easy, too.

The shape of the main portion of the above-described current-collectorconnector is approximately trapezoidal and, concerning the structure, itis more preferable that an external connection terminal be provided atthe short side and connecting plate portions at the long side.

The flow of electricity from a power generating element to an externalconnection terminal passes through the shortest distance from aconnection portion to the external connection terminal; hence, thetriangular edge portions 2 c locating at both sides of the terminalinsertion hole 10 of the current-collector connector, as shown in FIG.5, not only fail to serve a function as current collectors, but alsoincrease the battery weight and deteriorate the weight energy densitydue to their own existence. In contrast to this, the use of anapproximately trapezoidal shape allows a section unnecessary for thecurrent-collection function of the current-collector connector to be cutoff, so that a battery having a high weight energy density can beprovided without losing the current-collection function.

When the above-described power generating elements are configured bywinding positive and negative electrodes with a separator, and the crosssection perpendicular to the winding axis forms an elliptic cylindricalshape having linear part, it is preferable that the length of theabove-described pinching plates be shorter than that of the linear partof said power generating elements. The reason for this is that theconnection is easy and the reliability is also improved.

Moreover, when the power generating element forms an ellipticcylindrical shape, it is desirable that a set of above-describedconnecting plate portions be present per power generating element, thatone above-described pinching plate be present per connecting plateportion, that a set of connecting plate portions be disposed so as tohold the end portion of the power generating element from the outside,and that the pinching plate be disposed so as to lie at the outside ofthe connecting plate portion and at the center of the winding of thepower generating element. This allows the efficiency of the connectionwork and the reliability of the connection to be improved.

In addition, it is preferable that a battery case be equipped withexternal connection terminals, and that this external connectionterminal be connected to a current-collector connector. The reason forthis is that the external current drawing structure can be configuredeasily.

When a battery case is equipped with external connection terminals, itis preferable to be equipped with battery terminals, which are set onthe exterior of the battery case, and terminal connection members, whichare disposed on the exterior of the above-described battery case andconnected and fixed to the outward protruding portion of said batteryterminal, and to connect an external connection terminal through saidterminal connection member.

The external connection terminal is not only locked on but also firmlyconnected and fixed to the terminal connection member; thereforecharging/discharging current can pass through the section where theexternal connection terminal comes in contact with a connection memberof an external circuit directly or through a clamping member and thelike as well as the section where the connection member of the externalcircuit comes in direct contact with the terminal connection member;hence, it becomes possible to reduce the contact resistance at theterminals and improve the battery performance.

In addition, when the current-collector connector main portion forms anapproximately trapezoidal shape, it is desirable that an terminalinsertion hole for external connection be formed at a section near theshort side of the approximately trapezoidal shape of saidcurrent-collector connector main portion, that one end of said externalconnection terminal be connected and fixed to said terminal insertionhole for external connection in the inside of the battery case, and thatthe other end be derived to the outside of the battery case. The reasonfor this is that the volume efficiency becomes high and the currentdrawing structure can be configured easily.

Moreover, regarding the terminal insertion hole for external connection,when the distance from the center of the short side of the approximatelytrapezoidal shape of said current-collector connector main portion tothe center of said terminal insertion hole is referred to as D and thediameter of the terminal insertion hole for external connection isreferred to as R, it is preferable that R be not less than 0.5 D.

If R is set less than 0.5 D, the intensity in the vicinity of theterminal insertion hole declines and the vibratility resistancedeteriorates; therefore, failure or bad connection occurs in thissection during the use of the battery, thereby causing a decrease inbattery reliability. If R is set greater than 4 D, a section unnecessaryfor the current-collection function increases and this results in anincrease in the battery weight; therefore, it is preferable that R benot greater than 4 D. In addition, regarding the approximatelytrapezoidal shape, an isosceles triangle may be employed as an extremecase; however, if this is the case, an angular shape having a ridgelonger than R is preferable to a shape having a completely acuminatecrest.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an assembly perspective view showing an embodiment of thepresent invention.

FIG. 2 is a cross-section view showing a state where a connecting plateportion and an electrode are inserted in a pinching plate.

FIG. 3 is a view showing the configuration of a power generatingelement.

FIG. 4 is an assembly perspective view showing an embodiment of thepresent invention.

FIG. 5 is a perspective view showing an embodiment of thecurrent-collector connector which is used in the present invention.

FIG. 6 is an assembly perspective view showing an embodiment of thepresent invention.

FIG. 7 is an assembly perspective view showing an embodiment of thepresent invention.

FIG. 8 is a view showing a prior art example.

PREFERRED EMBODIMENTS OF THE INVENTION

Hereinafter, embodiments of the present invention will be described withreference to the accompanying drawings.

FIG. 1 is an assembly perspective view showing an embodiment of thepresent invention, and FIG. 2 is a cross-section view showing a statewhere a connecting plate portion and an electrode are inserted in apinching plate.

The embodiment describes a large non-aqueous electrolyte secondarybattery. In this non-aqueous electrolyte secondary battery, as shown inFIG. 1, two power generating elements 1, 1 of an elliptic cylindricalshape are aligned and connected in parallel. Each power generatingelement 1 has the same configuration as that of the prior art, where thealuminum foil at the side-edge portions of a positive electrode 1 aprotrudes from one end face of the elliptic cylindrical shape and thecopper foil at the side-edge portions of a negative electrode 1 bprotrudes from the other end face.

The above-described two power generating elements 1, 1 are alignedhorizontally so that the flat sides of each elliptic cylindrical shapeoverlap each other in an upright stance. And, current-collectorconnecting plates 2, 2 are disposed at both ends of these two powergenerating elements 1, 1, respectively. The current-collector connectingplates 2, 2 are made of metal plates thick enough to obtain a largecurrent capacity, respectively; a plate for the positive electrode 1 aside to be disposed at one end of the power generating element 1 is madeof an aluminum-alloy plate, and a plate for the negative electrode 1 bside to be disposed at the other end is made of a copper-alloy plate.Each current-collector connecting plate 2 consists of a main portion 2a, which is horizontally disposed and forms an approximately trapezoidalshape, and four elongated connecting plate portions 2 b, which areprovided so as to protrude downward from the base (long side) of thistrapezoidal main portion. In addition, on each connecting plate portion2 b, convex portions protruding from the plate face are formed atseveral points at arbitrary intervals. That is, each current-collectorconnecting plate 2 is formed as follows: a trapezoidal main portion 2 aand four elongated connecting plate portions 2 b, which extend straightin a tine shape from the base of this trapezoidal portion, are punchedin an aluminum-alloy plate or a copper-alloy plate by press work andconvex portions are formed on each connecting plate portion 2 b; theseconnecting plate portions 2 b are folded at the base of them at a rightangle with respect to the main portion 2 a; and each folded connectingplate portion 2 b is twisted at 90 degrees at the base, respectively. Inaddition, these four connecting plate portions 2 b are coupled into twopairs side by side, and the sides facing each other in each pair of twoconnecting plate portions 2 b are twisted so as to turn in the oppositedirection with respect to the main portion 2 a. And, due to this twist,the convex portions on each connecting plate portion 2 b are provided soas to protrude in the direction that a pair is facing each other.

The length of the twisted portion in the protruding direction of saideach connecting plate portion 2 b, L, is set longer than the thicknessof this connecting plate portion 2 b, T. The reason for this is thatwhen the length L is shorter than the thickness T, precipitous twistingis applied to this connecting plate portion 2 b, stress is concentratedon the twisted portion, and electronic conductivity deteriorates.

In the above-described each current-collector connecting plate 2, themain portion 2 a is disposed over both end portions of the two powergenerating elements 1, 1, and connecting plate portions 2 b are providedso as to be disposed along the end faces of these power generatingelements 1, 1. That is, at the end face side of each power generatingelement 1 from which the aluminum foil of the positive electrode laprotrudes, the current-collector connecting plate 2 made of analuminum-alloy plate is disposed, and at the other end face side fromwhich the copper foil of the negative electrode 1 b protrudes, thecurrent-collector connecting plate 2 made of a copper-alloy plate isdisposed. In addition, a pair of two connecting plate portions 2 b isdisposed along both sides of the metal foil of the positive electrode 1a or the negative electrode 1 b which protrudes from the end face ofeach power generating element 1. Here, at both end faces of each powergenerating element 1, the metal foil of the positive electrode 1 a orthe negative electrode 1 b sticks out and protrudes in a wound state andan elliptic cylindrical shape; therefore, it is possible to divide thesection of the linear part between the bent sides of the ellipticcylindrical shape, where sheets of such metal foil vertically overlapeach other, into two halves from side to side with respect to thewinding axis. And, the pair of two connecting plate portions 2 b beingdisposed every end face of each power generating element 1 is disposedrespectively outside the metal foil overlapping portions being separatedfrom side to side. In this case, a pair of two connecting plate portions2 b is twisted in the direction to which the inner sides beingoriginally laid opposite each other escape from the power generatingelement 1; therefore, the metal foil protruding from the end face ofeach power generating element 1, especially the upper bent portion, cannaturally fit in between the two connecting plate portions 2 b composinga pair.

After the current-collector connecting plate 2 is disposed as abovedescribed, the metal foil of the positive electrode 1 a and the negativeelectrode 1 b in the power generating element 1 is connected and fixedto each connecting plate portion 2 b by means of a pinching plate 4(FIG. 2.) That is, in each end face of each power generating element 1,the linearly overlapping portions of the metal foil are first separatedfrom side to side and put along the connecting plate portion 2 b of therespective sides, and these connecting plate portion 2 b and metal foilare inserted and held in the pinching plate 4. Accordingly, to theinside faces of the two connecting plate portions 2 b composing a pair,the metal foil overlapping portions being divided into halves from sideto side are closely appressed. And, ultrasonic welding is performed fromboth sides of each pinching plate 4 where the connecting plate portion 2b and the metal foil are held as above described, thereby allowing theseconnecting plate portion 2 b and metal foil of the positive electrode 1a or the negative electrode 1 b to be joined. Each pinching plate 4 isprovided by folding a strip of relatively thin metal plate into two atthe center along a long side; the pinching plate 4 made of thealuminum-alloy plate is used for the positive electrode 1 a side, andthe pinching plate 4 made of the copper-alloy plate is used for thenegative electrode 1 b side. These pinching plates 4 are used only forthe welding and the firm connection and fixing of the connecting plateportion 2 b and the metal foil; therefore, a large current capacity isnot necessary in particular, and a metal plate having an adequatethickness to allow optimal ultrasonic welding can be used. In eachconnecting plate portion 2 b, in addition, the convex portions 2 b 1 areformed on the inside face which overlaps with the metal foil; therefore,such metal foil can receive ultrasonic energy at each convex portion ina centralized manner, thereby allowing the welding to be performedsurely.

In the above-described pinching plates 4, the length should be shorterthan that of the linear part in the cylindrical shape of the metal foilof the positive electrode 1 a or the negative electrode 1 b protrudingfrom the end face of the power generating element 1. This allows thepinching plates 4 to hold only the linear part of the metal foiltogether with the connecting plate portion 2 b. The reason for this isthat if the length of the pinching plate 4 is longer than that of thelinear part of the metal foil, the pinching plate 4 would hold the upperand lower bent sides of the cylindrically protruding metal foil, therebycausing a fear that these portions of the metal foil are forcedly pulledtoward the pinching plate 4 and damaged.

Positive and negative electrode terminals 3, 3 of a non-aqueouselectrolyte secondary battery of the present embodiment are respectivelyconfigured with a rivet terminal (an external connection terminal) 3 a,a terminal connection rod (a terminal connection member) 3 b, and aterminal bolt (a battery terminal) 3 c. The rivet terminal 3 a isprovided in such a manner that a cylindrical caulking portion protrudesfrom the upper and lower faces of a square flange with four chamferedcorners, made of aluminum or aluminum alloy if the terminal 3 is usedfor the positive terminal, and made of copper or copper alloy if theterminal 3 is used for the negative terminal. In this rivet terminal 3a, the caulking portion in the lower part comes in contact with anelectrolyte solution; therefore, in case of a non-aqueous electrolytesecondary battery, for the positive terminal side it is necessary to usethe aluminum, aluminum alloy or the like which does not dissolve in anon-aqueous electrolyte solution, and for the negative terminal side itis necessary to use the copper, copper alloy or the like which does notalloy with a negative active material. The terminal connection rod 3 bis made of a copper-alloy metal plate of a rectangular shape, at bothends of which through-holes are made. In addition, the terminal bolt 3 cis a stainless steel hexagon bolt, where a bolt portion is provided soas to upwardly protrude from the upper face of the hexagonal headportion. These terminal connection rod 3 b and terminal bolt 3 c do notcome in contact with an electrolyte solution; therefore, for use as theterminal connection rod 3 b, copper alloy having high electricconductivity and sufficient mechanical strength is used in particularand, for use as the terminal bolt 3 c to be connected with the externalcircuit, stainless steel having high mechanical strength and sufficientelectric conductivity is used in particular.

The main portions 2 a, 2 a of the above-described current-collectorconnectors 2, 2 are disposed, practically before being attached to thepower generating elements 1, 1, at both end portions of the undersurfaceof a cover plate 6 with lower insulating sealants 5, 5 therebetween,respectively, as shown in FIG. 4. In addition, at both end portions ofthe top surface of the cover plate 6, rivet terminals 3 a, 3 a, terminalconnection rods 3 b, 3 b, and terminal bolts 3 c, 3 c are disposed withupper insulating sealants 7, 7 therebetween, respectively. In each rivetterminal 3 a, however, the tip of the caulking portion in the lower partis fitted in a through-hole (a terminal insertion hole) being providedin the main portion 2 a of the current-collector connector 2 via thethrough-holes being provided in the lower insulating sealant 5, thecover plate 6 and the upper insulating sealant 7, and connected andfitted by caulking. Then, the rivet terminal 3 a is isolated from thecover plate 6 by means of the insulating sealants 5, 7. In addition,when the caulking portion in the lower part of the rivet terminal 3 aand the main portion 2 a of the current-collector connector 2 arecaulked, the insulating sealants 5, 7 come to hold and press the coverplate 6; hence, the through-hole on this cover plate 6 is sealed. Ineach terminal connection rod 3 b disposed at both end portions of thetop surface of the cover plate 6 with the upper insulating sealants 7, 7therebetween, respectively, the caulking portion in the upper part ofthe rivet terminal 3 a is fitted in one through-hole from the underneathand connected and fitted by caulking, and the bolt portion of theterminal bolt 3 c is fitted in the other through-hole from theunderneath. Then, a hexagonal head portion of the terminal bolt 3 c isfitted in a hexagonal concave portion of the upper insulating sealant 7,thereby prevented from slewing. In this terminal bolt 3 c, by leavingthe bolt portion fitted and locked in the through-hole of the terminalconnection rod 3 b, it is possible to make the bolt portion be connectedand fitted to the terminal connection rod 3 b only when anexternal-circuit connection member is put on this bolt portion andfastened by a nut, or it is possible to connect and fit the head portionor the like in advance to the terminal connection rod 3 b by welding orthe like. As described above, when the terminal bolt 3 c is connectedand fitted in advance to the terminal connection rod 3 b, even if theexternal-circuit connection member is not fastened tightly by the nut,current flows steadily from this terminal connection rod 3 b to the areawhere the nut comes in contact with the connection member through theterminal bolt 3 c, as well as the area where the terminal connection rod3 b comes in direct contact with the connection member, so that thecontact resistance with the terminal 3 and the connection member can bereduced.

As described above, the terminals 3, 3 are disposed at both end portionsof the top surface of the cover plate 6, and the current-collectorconnectors 2, 2 are mounted at both end portions of the undersurface ofthe cover plate 6, and then, as described above, the power generatingelements 1, 1 are connected to these current-collector connectors 2, 2.And, these two power generating elements 1 are housed inside a stainlesssteel battery case 8 of an enclosure type, and the upper opening of thisbattery case 8 is covered with the cover plate 6. And, the circumferenceof the cover plate 6 is sealed by welding, the inside of the batterycase 8 is filled with an electrolyte solution, and this inside is sealedhermetically, thereby producing a non-aqueous electrolyte secondarybattery. In the non-aqueous electrolyte secondary battery, two powergenerating elements 1 are housed in a horizontal arrangement so that theflat side faces of the elliptic cylindrical shape are in an uprightposition, and the terminal bolts 3 c of the terminals 3 protrude fromboth end portions of the top surface of the cover plate 6; therefore,the efficiency of installation space becomes satisfactory.

According to the non-aqueous electrolyte secondary battery configured asabove described, the positive electrode 1 a or the negative electrode 1b of each power generating element 1 and the terminal 3 are connectedthrough the main portion 2 a and connecting plate portions 2 b of thecurrent-collector connector 2 having a large current capacity;therefore, it becomes possible to flow sufficiently largecharging/discharging current. Furthermore, the metal foil of thepositive electrode 1 a or the negative electrode 1 b of each powergenerating element 1 is connected to the connecting plate portion 2 b byultrasonic welding through the pinching plate 4 consisting of a somewhatthin metal plate; therefore, the welding is performed adequately so thatthe metal foil does not peel off easily.

In addition, the main portion 2 a of the current-collector connector 2is displaced horizontally over the two power generating elements 1, 1,thereby making the connection with the terminal 3 through the coverplate easy, and the connecting plate portion 2 b is folded downward,twisted, and protruded from this main portion 2 a, thereby allowing theface of this connecting plate portion 2 b to be set along the verticalmetal foil of the positive electrode 1 a or the negative electrode 1 bprotruding from the end face of each power generating element 1;therefore, the connection with the metal foil becomes easy. That is,with not being twisted, each connecting plate portion 2 b lies in adirection perpendicular to the metal foil, and this makes the connectionnot easy. In addition, when the connecting plate portion 2 b of thecurrent-collector connector 2 is formed by folding down a plate whichprotrudes toward both sides along the alignment direction of the powergenerating elements 1, 1 with respect to the main portion 2 a, the faceof the connecting plate portion 2 b can be set along the metal foilprotruding from the end face of the power generating element 1, thoughonly one connecting plate portion 2 b can be allocated to each powergenerating element 1, so that in case of a battery where three or morepower generating elements 1 are disposed side by side, it becomesimpossible to perform current collection from the one or more powergenerating elements 1 locating in the middle. Furthermore, thecurrent-collector connector 2 of the present embodiment can be producedonly by providing simple processes of punching, folding, and twisting inone sheet of metal plate.

In addition, a pair of two connecting plate portions 2 b is disposed perend face of each power generating element 1; therefore, even if thewidth of the connecting plate portions 2 b is made narrower, sufficientcurrent capacity can be attained, and the amount of the metal foilprotruding from this end face can be reduced. Furthermore, the metalfoil protruding from each end face of each power generating element 1 isinserted between the pair of two connecting plate portions 2 b alongtheir twisting direction; therefore, the assembly work becomes easy.

In the above-described embodiment, ultrasonic welding was mentioned asthe means of connecting the connecting plate portion 2 b and the metalfoil of the positive electrode 1 a or the negative electrode 1 b intothe pinching plate 4; however, welding can be performed using otherwelding methods such as spot welding or the like. In addition, insteadof performing such welding, by applying firm pressure on the pinchingplate 4 from the outside, the connecting plate portion 2 b and the metalfoil can be crimped. In this case, unlike in the case of welding, it isnecessary to use a somewhat thick metal plate for the pinching plate 4so that the power generating element connection portion 2 b and themetal foil can be firmly crimped and supported.

Moreover, to the connecting plate portion 2 b, even if convex portionsare not formed on it, the metal foil can be firmly welded or crimped. Inaddition, in the above-described embodiment, the pinching plate 4 wasmentioned as being used for connecting the connecting plate portion 2 band the metal foil of the positive electrode 1 a or the negativeelectrode 1 b; however, it is possible to make connection by usingconnecting parts other than the pinching plate 4 or by using none of theconnecting parts.

In addition, in the above-described embodiment, the non-aqueouselectrolyte secondary battery was mentioned as being configured bydisposing two power generating elements 1, 1 side by side; however, thenumber of the power generating elements 1 is not limited; hence, anynumber, one or more, of power generating elements 1 can be used in thebattery, and the battery is not to be considered limited to anon-aqueous electrolyte secondary battery, either. Moreover, in theabove-described embodiment, a pair of two connecting plate portions 2 bof the current-collector connector 2 was mentioned as being disposed perpositive or negative electrode of each power generating element 1,respectively; however, at least one or more connecting plate portions 2b can be disposed at the positive or negative electrode of each powergenerating element 1, respectively.

In addition, in the above-described embodiment, the terminal 3 wasmentioned as being configured with the rivet terminal 3 a, the terminalconnection rod 3 b, and the terminal bolt 3 c; however, theconfiguration of the terminal 3 is not limited specifically; hence, itcan be configured with a single part such as shown in FIG. 8.

In addition, in the above-described embodiment, the wound type powergenerating element 1 of an elliptic cylindrical shape was explained;however, even in case a laminated type power generating element 1 isused, the metal foil of the positive electrode 1 a or the negativeelectrode 1 b protruding from the end face of the lamination layers canbe connected and fixed in the same manner. Moreover, in theabove-described embodiment, the battery exterior consisting of thebattery case 8 and the cover plate 6 was exemplified; however, theconfiguration of the battery exterior is not limited specifically. Inaddition, in the above-described embodiment, the non-aqueous electrolytesecondary battery was explained; however, the type of the battery is notlimited specifically, either.

FIG. 5 is a perspective view showing an embodiment of thecurrent-collector connector which is used in the present invention, FIG.6 is an assembly perspective view showing an embodiment of the presentinvention, and FIG. 7 is an assembly perspective view showing a batterystructure which employs the power generating element 1 and thecurrent-collector connector 2 shown in FIG. 6.

In this non-aqueous electrolyte secondary battery, as shown in FIG. 6,four of the power generating element 1 of an elliptic cylindrical shapeare closely aligned and connected in parallel. In each power generatingelement 1, the aluminum foil at the side-edge portions of a positiveelectrode 1 a protrudes from one end face of the elliptic cylindricalshape, and the copper foil at the side-edge portions of a negativeelectrode 1 b protrudes from the other end face.

The above-described four power generating elements 1 are aligned closelyso that the flat sides of each elliptic cylindrical shape come incontact with each other, and the connecting plate portions 2 b ofcurrent-collector connecting plates 2 are disposed respectively at bothend faces of these power generating elements 1. Regarding thecurrent-collector connecting plates 2, the one to be disposed at one endface of the power generating elements 1 is made of an aluminum-alloyplate, and the one to be disposed at the other end face is made of acopper-alloy plate. In addition, for these current-collector connectingplates 2, somewhat thick metal plates are used so that large currentduring high rate discharge can flow sufficiently. In this example, athickness of 1.7 mm is used for either plate.

The main portions 2 a of these current-collector connectors arehorizontally-disposed metal plates which form a rather flat,approximately isosceles triangular shape (in the present application,this shape is considered included in an approximately trapezoidalshape), and eight elongated connecting plate portions 2 b are providedso as to protrude downward from the base of this triangular shape. Theseconnecting plate portions 2 b are formed in such a manner that elongatedmetal plates are punched in a metal plate for the current-collectionconnection 2 by press work, and that the obtained portions are foldeddownward and twisted at 90 degrees. In addition, as shown in FIG. 2,several protruding convex portions 2 b 1 are formed on one surface ofthe metal plate.

The above-described current-collector connectors 2 are provided so as tobe disposed over both end portions of the four power generating elements1, respectively, and the connecting plate portions 2 b are provided soas to be disposed along the end faces of these power generating elements1. At the end face side of the power generating elements 1 from whichthe aluminum foil of the positive electrode la protrudes, thecurrent-collector connecting plates 2 made of an aluminum-alloy plateare disposed, and at the end face side from which the copper foil of thenegative electrode 1 b protrudes, the current-collector connectingplates 2 made of a copper-alloy plate are disposed. In addition, twoconnecting plate portions 2 b are disposed at every end face of eachpower generating element 1.

Here, at the end face of each power generating element 1, the aluminumfoil of the positive electrode 1 a or the copper foil of the negativeelectrode 1 b sticks out in a wound state and an elliptic cylindricalshape; therefore, the section where such metal foil vertically aligns inbundle is divided from side to side with respect to the winding axis.And, the two connecting plate portions 2 b being disposed every powergenerating element 1 are disposed respectively outside the bundle of themetal foil which are separated from side to side. In addition, as shownin FIG. 2, these two connecting plate portions 2 b are twisted at 90degrees in an opposite direction from each other so that the face of theprotruding side of the convex portion 2 b 1 can face inside, or the sideof the metal foil bundle.

After the connecting plate portions 2 b of the current-collectorconnector 2 are disposed as above described, the bundle of the metalfoil of the positive electrode 1 a or the negative electrode 1 b is heldtogether with the connecting plate portion 2 b by means of a pinchingplate 4. The pinching plate 4 is provided by folding a strip of metalplate into two along a long side; the aluminum-alloy plate is used forthe connecting plate portions 2 b of the positive electrode 1 a side,and the copper-alloy plate is used for the connecting plate portions 2 bof the negative electrode 1 b side.

And, ultrasonic welding is performed from both sides of these pinchingplates 4; hence, the connecting plate portion 2 b of thecurrent-collector connector 2 and the bundle of the metal foil of thepositive electrode 1 a or the negative electrode 1 b, which are held inthe respective pinching plates 4, are welded.

The parts of an approximately isosceles triangular shape of the positiveand negative current-collector connectors 2 which are disposed over bothends of the power generating elements 1, as shown in FIG. 7, are mountedat both sides of the undersurface of a rectangular cover plate 6 withthe insulating sealants 5 therebetween. The cover plate 6 is made of astainless steel plate, at both sides of whose top surface the positiveand negative terminals 3 are disposed with other insulating sealants 7therebetween. Regarding these terminals 3 a, the lower end portion ispassed through the cover plate 6 into a terminal insertion hole 10 beingprovided near the vertex of the approximately isosceles triangular shapeof the respective current-collector connectors 2, and connected andfixed by caulking.

In addition, the upper end portion of these terminals 3 a is connectedand fixed by caulking to a connection conductor 3 b which locks anexternal terminal 3 c being disposed on the insulating sealant 7.Regarding these terminals 3 a, the one which is made of aluminum-alloyis used for the current-collector connector 2 of an aluminum-alloyplate, and the one which is made of copper-alloy is used for thecurrent-collector connector 2 of a copper-alloy plate.

However, the connection conductors 3 b and the external terminals 3 c donot come in contact with an electrolyte solution; therefore, steelalloy, iron alloy or the like, the strength of which is higher than thatof aluminum alloy, copper alloy or the like, is used. The insulatingsealants 5, 7, which are disposed on the top and the back of the coverplate 6, are the resin molding plates which isolate and seal the coverplate 6 from the current-collector connectors 2, and the terminals 3 a(corresponding to external connection terminals), the connectionconductors 3 b (corresponding to terminal connection members) and theexternal terminals 3 c (corresponding to battery terminals) 3C.

Above-described four power generating elements 1 are housed in a batterycase body, which is not illustrated, and the cover plate 6 is fitted inan upper end opening of this battery case body and firmly fixed bywelding or the like. And, the inside of this battery case body is filledwith an electrolyte solution, thereby producing a non-aqueouselectrolyte secondary battery.

According to the above-described battery structure, the terminal 3 amade of aluminum alloy or copper alloy is connected and fixed to theconnection conductor 3 b made of steel alloy, iron alloy or the like,and the connection with an external circuit is made through the externalterminal 3 c being locked with this connection conductor 3 b; therefore,there is no need to directly cramp the terminal 3 a made of low-strengthaluminum alloy or copper alloy with a screw, and no fear of damaging theterminal 3 a by fastening this screw cramp or deforming the terminal 3 adue to vibration or shock.

In addition, in the above-described embodiment, the metal foil of thepositive electrode 1 a or the negative electrode 1 b was explained asbeing disposed only at the one side of the connecting plate portion 2 b;however, the metal foil may be disposed at both sides so that both sidescan be held in the pinching plate 4. Moreover, in the above-describedembodiment, two connecting plate portions 2 b were disposed at one endface of each power generating element 1; however, the number of thisconnecting plate portions 2 b to be disposed is not limited. Forexample, one power-generation connecting plate portion 2 b may bedisposed per end face of each power generating element 1, or the metalfoil protruding from the end faces of the two power generating elements1 lying next to each other can be welded or crimped together to this oneconnecting plate portion 2 b.

The current-collector connectors 2 used in the battery such as shown inFIG. 6 were formed by cutting and removing the triangular edges 2 c ofboth sides of the terminal insertion hole 10 of the current-collectorconnector 2 such as shown in FIG. 5; however, it is possible to use themwithout cutting both sides. However, in the comparison of the batteriesemploying those with these two shapes, although no difference is notedin their current collection efficiencies, the battery shown in FIG. 6 isfound to be lighter in weight and higher in weight energy density.

In the above-described embodiment, a non-aqueous electrolyte secondarybattery was explained; however, any type of battery may be used. Forreference's sake, the basic configuration of the non-aqueous electrolytesecondary battery in the present invention can be exemplified as follow.

First, as a positive active material, various materials can be usedincluding titanium dioxides, lithium-cobalt composite oxides,spinel-type lithium manganese oxides, vanadium pentoxides, andmolybdenum trioxides; among them, lithium-cobalt composite oxides(LiCoO₂) and spinel-type lithium manganese oxides (Li_(x)Mn₂O₄) arecapable of performing charge/discharge with an extremely electropositivepotential not less than 4 V (4Li/Li⁺); hence a battery having a highdischarge voltage can be provided by using these as a positiveelectrode.

Regarding a positive electrode, aluminum foil having a thickness of 10to 30 μm is common as a current collector, typically both sides of saidcurrent collector are coated with an active material layer, and it ispreferable that the active material layer be 50 to 150 μm (per one face)in thickness, 1.8 to 3.0 g/cc in density, and 25 to 45% in porosity interms of life performance and charge/discharge characteristics.

To a negative electrode, various materials can be applied includinglithium metal, Li-Ai alloys capable of undergoing absorption/desorptionof lithium, or carbon materials; among them, carbon materials have theadvantage of allowing a battery to have high safety and long cycle life.

In this case, copper foil having a thickness of 10 to 20 μm is suitableas a current collector, and it is preferable that the active materiallayer be 45 to 125 μm (per one face) in thickness, 1.15 to 2.5 g/cc indensity, and 25 to 45% in porosity in terms of life performance andcharge/discharge characteristics.

In addition, an electrolyte solution is prepared as follows: a solventof low viscosity such as 1,2-dimethoxyethane, dimethyl carbonate, ethylmethyl carbonate or diethyl carbonate is mixed into a solvent of highconductivity such as propylene carbonate, ethylene carbonate,7-butyrolactone or sulfolane, and then lithium perchlorate, lithiumtrifluoromethan sulfate or lithium hexafluorophosphate is added as asolute to this mixture. Instead of using such liquids, it is possible touse the electrolytes of all solid state or gel electrolytes, or theseelectrolytes in combination with liquid electrolytes.

An electrode can be produced by coating metal foil with the slurry whichis prepared by mixing, for example, an active material, a binder, and asolvent. For use as a binder, fluorocarbon resins such aspoly(vinylidene fluoride) and poly(tetrafluoroethylene) are superior inoxidation-reduction resistance and electrolyte solution resistance;among them, poly(vinylidene fluoride) soluble in organic solvent is mostwidely used at present because it allows easy preparation of slurry. Thepreferable amount is 2 to 6 wt. % for use in a positive electrode, and 6to 10 wt. % for use in a negative electrode.

For use as a separator, a porous resin film having a thickness of 20 to60 μm is preferable; however, polymer electrolyte membrane can also beused.

INDUSTRIAL APPLICABILITY

According to the battery of the present invention, even when powergenerating elements and terminals are disposed in consideration of spaceefficiency, by the use of a current-collector connecting plate of asimply processed metal plate, it becomes possible to perform currentcollection efficiently. Furthermore, it becomes possible to make securethe connection between the electrodes in the power generating elementsand the connecting plate portions of the current-collector connectingplates, and possible to perform the assembly work easily.

1. A battery comprising: an electrode, an isolation material, a powergenerating element configured by winding said electrode and saidisolation material into an elliptic cylindrical shape, comprising twoend portions, two flat sides and two curved sides, and acurrent-collector connector comprising a plate-like main portion and aconnecting plate portion, wherein said main portion is disposed alongone of said curved sides, said connecting plate portion is protrudedfrom said main portion by bending, said connecting plate portion istwisted so that a face of said connecting plate portion is set alongsaid electrode, and said face of said connecting plate portion isconnected to said electrode.